1. Field of The Invention
The present invention is generally related to devices in submarine gel electrophoresis and is particularly directed to improvements of conventional submarine gel apparatus for decreasing temperature in gel matrix so that higher voltage can be applied in electrophoresis.
2. Description of the Prior Arts
Gel electrophoresis is one of the most commonly utilized tools in biomedical researches and industries. In gel electrophoresis, a sample of mixed biomolecules is applied into sample wells of a gel matrix, a buffer conducts an electric field from a pair of electrodes to the gel matrix, and the components in the sample migrate across the gel matrix. Different components migrate at different speed so that they can be separated from each other in electrophoresis. The migration rate is directly related to the voltage of the electric field applied. Higher voltage generates higher migration rate under given condition.
Agarose gel is one of the most popularly used gel matrix. An agarose gel matrix is formed from an agarose gel solution by a decrease of temperature. The formed agarose gel matrix is readily reversible to solution format whenever the temperature rises to a certain point. The properties of agarose gel matrix are significantly altered when the temperature changes due to the nature of the gel forming mechanism. Thus, it is critical for agarose gel electrophoresis to maintain the gel matrix at low temperature.
Conventional submarine gel electrophoresis is the most commonly used format for agarose gel due to its simplicity in manipulation. The gel matrix is usually immersed completely in a buffer. A typical feature of this format is that electric current travels from one electrode to another electrode via both a gel pathway through the gel matrix and a buffer pathway through the buffer around the gel matrix. The electric current in buffer pathway has no function for the migration of samples but generates unwanted massive heat, which severely prevents heat transfer from the gel matrix to the buffer. The voltage applied to submarine gel electrophoresis is, therefore, limited within low level range in order to maintain the gel matrix at low temperature.
The existence of a buffer pathway around gel matrix results in disadvantages:
(1) The electrophoresis has to be a slow process because the voltage applied must be limited within low level range to avoid generating excess heat which will otherwise distort the gel matrix. PA1 (2) A strong buffering capacity is required for maintaining PH balance under the heavy electric current condition. PA1 (1) The buffer is frequently disposed after each electrophoresis because it requires extra labor to separate buffer from water after electrophoresis. The buffer should be, otherwise, reusable for several times due to the elimination of the buffer pathway in Chen's device. The buffer reuse has extraordinary meaning for environment protection because there are usually some extremely hazard chemicals, such as Ethidium Bromide, mixed in the buffer. PA1 (2) In practice, electrophoresis may be, sometimes, stopped halfway for a brief view or manipulation of the gel matrix and then resumed to completion. A new buffer, in this case, is needed to add to the device, which generates more waste and extra operations. PA1 1. It provides the capacity of using the same buffer many times, the buffer life time in the present invention is significantly longer than that in conventional submarine gel devices, which is a meaningful contribution for environment protection. PA1 2. It provides the convenience of gel viewing and manipulation during electrophoresis without buffer change, which reduces buffer waste and user's operation.
These disadvantages are long-felt problems. Attempts have been made for pursuing improvement of the conventional submarine gel electrophoresis.
Audeh, U.S. Pat. No. 4,702,814, teaches a submarine gel device having a gas collecting means and a conduit for eliminating the requirement of having a strong buffering capacity in buffer system. But Audeh fails to recognize the basis of the requirement. A buffer pathway is inherited in his device. Thus, Audeh fails to accelerated the slow process of electrophoresis.
Hoefer, 1994 Catalog of Hoefer Scientific Instruments at page 30, teaches a submarine gel device having a coolant mixture in base chamber for accelerating the slow process of electrophoresis. Hoefer, However, also fails to recognize the basis of those disadvantages. A buffer pathway is still inherited in his device, which indicates that his acceleration is only a limited improvement.
Fairfield, U.S. Pat. No. 5,074,981, teaches a device for high speed gel electrophoresis. Fairfield recognizes the basis of those disadvantages so that the buffer pathway is removed from his device. But, Fairfield fails to find a correct solution to establish his improvement. To reach his high speed, Fairfield sacrifices the most attractive advantage of submarine gel electrophoresis, the simplicity, and replaces it with a series of delicate requirements, a series of complicate manipulations, a series of time-consuming steps, and a series of risk of failure. The extra time required for operating his device is much longer than the time saved by his device. Fairfield's device is, therefore, practically infeasible for most routine applications.
Chen, U.S. Pat. No. 5,549,806, teaches a device to reach high speed submarine gel electrophoresis. Chen has recognized the basis of those disadvantages and achieved his high speed with a simple strategy, using water to replace buffer. Chen's device, however, generates new concerns and limitations:
A device being able to reach high speed in submarine gel electrophoresis but without negative impact at other aspects remains unsolved and is highly desirable.